Alkylacetoacetic ester Alkylation

Acetoacetic ester is like a molecule of acetone with a temporary ester group attached to enhance its acidity. Ethoxide ion completely deprotonates acetoacetic ester. The resulting enolate is alkylated by an unhindered alkyl halide or tosylate to give an alkylacetoacetic ester. Once again, the alkylating agent must be a good SN2 substrate. 

Nitrosation of -substituted / -keto esters is accompanied by loss of the acyl group. -Alkyl-acetic esters, which are important for preparation of keto acids,260 are obtained in this way from C-alkylacetoacetic esters ... 

Acetoacetic ester is converted by sodiunL thexide into the sodioacetoacetic ester, which is then allowed to react with aa alkyl halide to form an alkylaceto-acetic ester (an ethyl alkylacetoacetate), CH3COCHRCOOC2H5 if desired, the alkylation can be repeated to yield a dialkylacetoacetic ester, CH3COCRR COO-C2H5. All alkylations are conducted in absolute alcohol. 

Esterification at room temp, with tetrachloroaluminic acid ether complex has been described The alcoholysis of a-mono-alkylacetoacetates to the corresponding esters and alkyl acetates has been accomplished with excellent yields A new modification of the Curtius degradation avoids the prepn. of acid chlorides by using in their place carboxylic alkoxyformic anhydrides intermediates well-known in peptide chemistry. Among recent developments in this latter field are the use of mixed anhydrides prepared with diphenylketene an improved peptide synthesis via azides prepared with nitrosyl chloride or butyl nitrite instead of aq. sodium nitrite and a rapid synthesis directly from acid hydrazides with N-bromosuccinimide Oligopeptides and /5-lactams have been synthesized from simple starting materials and isonitriles,... 

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